She’s the reason millions of copies of Alexander McCall Smith’s series of novels, which began with The No 1 Ladies’ Detective Agency, have been sold in the UK and around the globe. Some call her the Miss Marple of Botswana, and now jazzy R&B singer Jill Scott will play her in a TV series directed by Anthony Minghella, with scripts he wrote with Richard Curtis.

Harvey Weinstein’s studio Weinstein Co is backing the venture.

Idris, who played the astute bad guy Stringer Bell in the cult HBO drama The Wire, will be in an episode that begins shooting in Botswana in the middle of next month.

He could have taken a larger role, but wants to make more films.

"The bloke I play is a bad guy, he’s a wheeler-dealer and Mma Ramotswe has to deal with him," he says.

Idris was in town from his home in New York to appear alongside Gerard Butler and Thandie Newton in Guy Ritchie’s movie RocknRolla, which is about gangsters (of course!) who become involved with a stolen painting, a dishonest accountant and a posse of violent and sexually-uncertain henchmen.

Idris plays Mumbles, a hired goon who works for the accountant, and began rehearsals yesterday.

He pops up all over the place on American TV and gets to work with people such as Denzel Washington, Russell Crowe and Ridley Scott on the big screen.

But few realise that he’s an East End lad, and his parents still live in the area.

"There’s a disconnect there, because my parents have little idea of what I do in America," says Idris, who keeps homes in Manhattan, Los Angeles and is about to buy another in Atlanta.

His parents might be more impressed now that he’s going to meet Mma Ramotswe in the flesh.